Op de engelse MP-uitlegpagina staat:
Some mappers use the current “multipolygon” relation for combining touching inner rings:
An implementation of multipolygons should attempt to render these as if the touching rings were indeed one ring. This is the one case where OpenStreetMap use deviates from standard OGC Simple Features. In Simple Features, touching inner rings are not supported because they are unnecessary (why make two inner rings when you could combine them into one). In OpenStreetMap, they sometimes make sense if tagged individually, for example a forest with a clearing which is half occupied by a lake and half by farmland - you would have two “holes” in the forest, one being tagged as natural=water and the other as landuse=farmland.
Figure 8: Touching inner rings
Dus voor OSM zou het mogen.
De andere manier is volgens OGC Simple features, dat moet dus ook goed zijn, als je erop bedacht ben dat de tools dit doen en dat er daarbij een ongetagde extra way gecreëerd wordt.
